Dietary fat (depending on the source of course) is not bad. So lets say you had a product that blocked a very large portion of fat. Its effect would be to make you worse off than before and worsen your health. If you could selectively blocks certains fats that would be useful, but that doesn't exist.
Diet change is the best bet, once you've done that you can tweak things with the partitioners mentioned (i'm partial to gxr of course). Other products that can help you get the most out of your food are things like sesamin (a few brands out there now), our melting point (a tta product), etc. Another very inexpensive way is to help your digestive system out with probiotics and inulin (usually FOS/Inulin is dirt cheap).
Again, there is no real substitue for having a better diet and exercising. Those two are the foundation, and with that you can add several things to make it even better. Without it, no product will give you a lasting effect that you want, and can unfortunately create bigger problems after you stop.
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